ENS 42119
ENS Event | |
|---|---|
22:00 Nov 3, 2005 | |
| Title | Deficiency Found in Integrated Safety Analysis Program |
| Event Description | BACKGROUND:
Framatome ANP routinely vacuum transfers LEU powder into 55-gallon drums for storage in the BLEU facility 55-gallon drum warehouse. A change was implemented recently to also vacuum transfer LEU powder from 45-gallon drums into 55-gallon drums, also for storage in the BLEU facility 55-gallon drum warehouse. EVENT DESCRIPTION: On day shift November 3, 2005 at approximate 2:00 PST, a process operator vacuum transferred LEU powder enriched to (deleted) wt% 235U from a 45-gallon to a 55-gallon drum in the BLEU facility at the Richland site. This transfer was performed according to an approved standard operating procedure (SOP). This was the first such transfer under a recently approved nuclear criticality safety analysis (NCSA) part of the Integrated Safety Analysis (ISA) When the operator was preparing the newly filled 55-gallon drum for transfer to and storage in the warehouse, the Nuclear Inventory Management System (NIMS) would not print a label for the drum. Operations personnel contacted an NCS specialist about this issue. While troubleshooting this problem, the NCS specialist discovered that the LEU powder contained hydrogenous additives. He recognized that the Richland site ISA did not implement IROFS to prevent transfer of powder containing hydrogenous additives from 45-gallon to 55-gallon drums. At this point, the drum was sampled and locked in place pending further evaluation. The 45-gallon to 55-gallon transfer process was also placed out of service pending further evaluation. SAFETY SIGNIFICANCE OF EVENT: The safety significance of this event is very low. In accordance with the NCSA a 55-gallon drum filled with LEU powder, enriched to (deleted ) 235U with a bulk density of (deleted ) and containing (deleted ) wt% moisture, that is fully reflected by water has a keff of (deleted). A moisture value of (deleted) wt% is required in such a drum to reach a keff of 1.0. The drum involved in this event actually contained 115.4 kg of LEU powder enriched to (deleted) wt% 235U with a bulk density of (deleted) and containing (deleted) total moisture equivalence (moisture and moisture equivalent approved additives determined by follow up laboratory analysis). Based on total moisture equivalent content alone, the material in the drum would have to have more than (deleted) times the limit (deleted) and more than (deleted) times the actual amount (deleted) before criticality could occur in the drum. The actual enrichment and bulk density of the material involved in this event provide additional margin compared to the values required for criticality discussed in the previous paragraph. POTENTIAL CRITICALITY PATHWAYS INVOLVED (BRIEF SCENARIO(S) OF HOW CRITICALITY COULD OCCUR): Criticality could only occur if moderation control on the material placed in the drum is lost. This could hypothetically occur if powder containing over (deleted) times the allowed limit (deleted) were placed into the drum. CONTROLLED PARAMETERS (MASS, MODERATION, GEOMETRY, CONCENTRATION, ETC.): The process parameter controlled in this portion of the process is moderation. NUCLEAR CRITICALITY SAFETY CONTROL(S) OR CONTROL SYSTEM(S) AND DESCRIPTION OF THE FAILURES OR DEFICIENCIES: Within the 1SA the NCSA, E04-NCSA-323 version 3.0 accident sequence 1.4.1 description bounds this event. It states, "UO, powder containing greater than (deleted) wt% H2O equivalent is transferred to a 55-gallon drum from the BLEU powder preparation south addback station. Defense 1 for this accident sequence states, 'Moderation control: Any 45-gallon drum of UOX powder that does not have at least two independent determinations that it has (deleted) wt% or less moisture must be stored in a specially designated, locked storage grid to prevent accidental drum movement.' This is IROFS 1105 and was maintained throughout this event. At HRR, per SOP, if a drum contains greater than (deleted) wt% moisture and/or > (greater) wt% moisture equivalent additives, it is locked in a storage location. Only trained key custodians may unlock these storage locations for further processing or handling of the drum, Based on the moisture and moisture equivalent approved additive content of the powder, the drum involved in this event was not such a drum. Defense 2 for this accident sequence states, 'Moderation control: The programmable controller interfaces with NIMS to verify acceptable moisture content before it permits transfer valve to open.' This is IROFS 6002 and was maintained throughout this event for moisture content of the powder. As implemented, this IROFS does not verify that the powder to be transferred contains no hydrogenous additives. However, as an uncredited defense, before permitting the transfer valve to open, NIMS does verify that the powder contains s (deleted) wt% AZS and (deleted) wt% ALS, which is (deleted) wt% moisture equivalent approved additives. Therefore, on a total moisture and moisture equivalent basis, NIMS does verify that the powder contains less than (deleted) wt% total moisture equivalence. This is approximately (deleted) times less than the (deleted) wt% total moisture equivalence required to approach a keff value of (deleted). Defense 3 for this accident sequence states, Moderation control provided by an AEC [active engineered control]. An in-line moisture monitor is interlocked to shut off the vacuum blower and stop the rotary valve to prevent a significant amount of Uox powder containing greater than (deleted) wt% H2O from being transferred to the drum. This is IROFS 4704 and was maintained throughout this event for moisture content of the powder. This IROFS, however, will not detect dry hydrogenous additives. CORRECTIVE ACTIONS TO RESTORE SAFETY SYSTEMS AND WHEN EACH WAS IMPLEMENTED: After discovery of the deficiency, the drum was sampled and locked in place pending further evaluation. The 45-gallon to 55-gallon transfer process was also placed out of service pending further evaluation. |
| Where | |
|---|---|
| Framatome Anp Richland Richland, Washington (NRC Region 2) | |
| License number: | SNM-1227 |
| Reporting | |
| Part 70 App A (B)(2) | |
| Time - Person (Reporting Time:+16.63 h0.693 days <br />0.099 weeks <br />0.0228 months <br />) | |
| Opened: | Robert Link 14:38 Nov 4, 2005 |
| NRC Officer: | John Mackinnon |
| Last Updated: | Nov 4, 2005 |
| 42119 - NRC Website
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Framatome ANP Richland with Part 70 App A (B)(2) | |
WEEKMONTHYEARENS 558972022-05-13T02:10:00013 May 2022 02:10:00
[Table view]Part 70 App A (B)(2) Gamma Monitors NON-FUNCTIONAL ENS 425852006-05-17T19:30:00017 May 2006 19:30:00 Part 70 App A (B)(2) Postulated Criticality Due to Backflow to an Unfavorable Geometry Vessel ENS 421192005-11-03T22:00:0003 November 2005 22:00:00 Part 70 App A (B)(2) Deficiency Found in Integrated Safety Analysis Program 2022-05-13T02:10:00 | |